Improvement in capping screws



NTTED STATES PATENT GFFICE.

J. W. BISHOP, OF NEW HAVEN, OONNEOTIOUT.

IMPROVEMENT IN CAPPING SCREWS.

Specification forming part of Letters Patent No.- 59,3114, dated November 6, 1866.

To all whom it may concern: n

Be it known that I, J. W. BISHOP, of New Haven, in the county of New Haven and State of Connecticut, have invented a new Improvement in Capping Screws; and I do hereby declare the following, when taken in connection with the accompanying drawings and the letters of reference marked thereon, to be a full, clear, and exact description of the same, and which said drawings constitute part of this specication, and represent, in-

Figure l, a side view of the screw complete; Fig. 2, a top view; Fig. 3, a vertical central section of the screw; Fig. 4, a central section of the cap, and in Fig. 5 a central section of the screw capped.

My invention relates to capping that class of screws the heads of which are centrally perforated with a round or square hole; and consists in covering the head of the screw with a cap of sheet metal centrally perforated to correspond with the perforation in the head of the screw, the object being to give to the screw the appearance of brass, silver, or gold, as the case maybe 5 and to enable others skilled in the art to thus cap this class of screws,` I will proceed to describe my manner of so doing.

The screw to be capped is first formed in the usualmanner 5 but instead of nicking the head I drill, punch, or otherwise perforate the head A, as at a. (See Figs. 2 and 3.) This perforation may be round or square 5 but I prefer round.

The driver is made square-pointed, so that when pressed firmly into the head it will, if the perforation be round, indent itself sufficiently into the body of the head, so that the screw may be turned much more strongly than the ordinary nicked head.

The advantages of this construction over the ordinary nicking are several: first, the screwdriver cannot slip from its hold in the head;

` second, the head cannot split, however great the strain upon it; and numerous other advantages readily seen by those familiar with the use of such screws.

The cap for the screws is rst punched from a thin sheet of metal-brass or copperof the proper size, and centrally perforated to correspond with the perforation in the screw, preferring always a round perforation; then, in proper dies .formed for the purpose, the cap is struck into the form seen in section, Fig. 4; then, inverted in a die, the screw-head is set into the cap and the cap closed down over the head, as seen in Fig. 5. This manner of capping has one great advantage over capping nicked screws, which is this, that whereas a slot must be punched in the cap for nicked screws corresponding to the nick in the head, and great care has to be exercised in closing the cap over the head in order that the slot in the cap may correspond to the nick in the head, whereas b v the central perforation of the cap and head the one always corresponds to the other.

A second great advantage is this, that if in the nicked heads the cap is not perfectly tight thereon it is easily turned from its proper position, and the screw thus rendered useless, so that in the manufacture of such capped screws it is found necessary to examine each head before they are packed for market; whereas by this perforation, however much the cap may be turned, the perforation of the one always corresponds to the other. The head ofthe screw is then burnished or finished in any desired manner. v

I do not, as is evidenced by the foregoing, g Abroadly claim capping screws; neither do I claim a screw having its head centrally perfoi-ated.

What I claim as my invention, and desire to secure by Letters Patent, is-

The combination of a centrally-perforated 4 metal cap with a centrally-perforated screwhead, substantially in the manner herein set 

